The present invention relates to means for preventing electrification of an ink ribbon cassette.
Nowadays, in a printer or a typewriter, the case and many other parts of an ink ribbon cassette are made of synthetic resin. And it is necessary to provide a means for preventing the action of static electricity which is produced by friction between the ink ribbon and the guide rollers and the like. Once static electricity occurs, the smooth operation of the ink ribbon is hindered and the printer or the typewriter may operate erroneously due to the discharge of the accumulated static electricity.
In order to prevent any adverse effect due to static electricity, in one prior art system, a grounding point is provided at a printing head so that electric current may flow from the grounding point to a chassis through a flexible flat cable. And in another prior art system, a grounding point is provided in an ink ribbon cassette and the grounding point is designed to contact a chassis when the ink ribbon cassette is placed in the chassis.
In the former prior art system in which a grounding point and a flat cable are employed, the number of wires in the flat cable is increased and the flat cable becomes wide so that high costs result. And in the latter prior art system in which a grounding point is provided in the ink ribbon cassette, there is present a mechanical contact point between the grounding point and the chassis, and such a structure tends to result in insufficient electrical contact and, in addition, the number of parts is increased.